Bright nickel plating baths



United States Patent 9 Claims. (Cl. 260-290) This application is adivision of application Serial No. 266,032, now Patent No. 3,170,853,filed March 18, 1963.

This invention relates to a composition of organic bromides andchlorides useful for addition to electroplating baths, i.e. solutions ofwater-soluble nickel salts to improve the brightness of nickelelectrodeposited from such solutions. The organic bromide and chlorideadditives produce electro-deposits of nickel on base metals which arehighly lustrous, adherent and ductile.

The subject compounds are nitrogen heterocyclic derivatives belonging tothe 2- and 4-vinyl pyridine groups, reacted with allyl and methallylbromide or chloride to yield corresponding vinyl pyridinium compounds.These compounds can be represented by the following:

Pyridininm compounds In the above representation, R is an allyl ormethallyl group, R is vinyl, and may be substituted in the 2 or 4position of the pyridine. Of outstanding utility are the N-allyl-2 vinylpyridinium bromide, N-allyl-4-vinyl pyridinium bromide, and mixturesthereof; the corresponding chlorides are also useful; and, also, thecorresponding Nmethallyl-2-vinyl pyridinium bromide and chloride as wellas the N-methallyl-4-vinyl pyridinium bromide and chloride are useful.

The organic derivatives which are the basis of this invention and thepreferred concentration at which they are used in electroplating bathsare listed in Table I. They are used jointly with the sulfur compoundsdescribed in Table II. The sulfur compounds listed are a representativegroup useful for the purpose.

Although quaternary ammonium salts of nitrogen heterocyclics have beenpreviously identified as useful additives to bright nickel platingbaths, allyl bromide and chloride salts of 2 and 4 vinyl pyridine areunique for this application.

I have found that if the acid anion is a bromide or chloride, and if thenitrogen in the cation is quaternized with an allyl or methallyl group,a product is obtained which is water dispersible and produces a superiorbrilliant adherent nickel deposit when added to a nickel electroplatingbath containing the organic additives described in Table II.

The use of the compounds in accordance with this invention for producingbright nickel deposits is based on electro-depositing nickel from asolution of one or more nickel salts to which there has been added 0.001to 0.30 gram per liter of an allyl or methallyl 2- or 4-vinyl pyridiniumhalide as listed in Table I herein, together with 0.1 to 80 grams perliter of a sulfur compound in which the sulfur atom has a valence of 4or 6, and is selected from the group of aliphatic unsaturated sulfonicacids, mononuclear and binuclear aromatic sulfonic acids, heterocyclicsulfonic acids, mononuclear aromatic sulfinic acids, aromaticsulfonamides and sulfonimides (see Table II herein). The water solublealkali metal, ammonium magnesium, and nickel salts of the above compounds are used in combination with the quaternary 2- and 4-vinylpyridinium compounds in accordance with this invention.

The brightener additives used in the method of this invention Wereevaluated in 21 Hull cell using a standard Watts type bath containing330 grams of nickel sulfate hexahydrate/liter, 45 grams of nickelchloride per liter, 37.5 grams per liter of boric acid, operated at a pHof 3.5, and a temperature of 50 C. The nickel deposits were made onbrass Hull cell panels 2" by 3" by plating for five minutes at threeamperes. The concentrations and combination of organic additives whichgave brilliant mirror-like deposits of nickel over a wide currentdensity range are listed in Table III.

Lustrous and adherent nickel deposits were also obtained from bathshaving the following composition:

Grams/ liter Nickel sulfate 6H O 330 Sodium chloride 30 N-allyl 2-vinylpyridinium bromide 0.01 Naphthalene trisulfonic acid 2.0-8.0 Nickelfluoborate 225 Nickel chloride 6H O 30 Boric acid 30 N-allyl 4-vinylpyridinium bromide 0.005.l0 2,5-naphthalene disulfonic acid 2.88.0

The above plating bath compositions are illustrative of the ranges ofbath compositions which have been tested successfully and do notindicate any limit of the bath composition which can be employed inaccordance with the invention. Actually, useful ranges of nickelconcentration are from 200-400 grams per liter; whether the nickel bepresent as sulfate, chloride, nitrate or fluoborate. The concentrationsof the organic sulfur additives and the vinyl pyridinium additiveslisted in the tables are by no means limiting. Preferred operativeranges are given. A considerable variation in concentration of theseagents is permissible depending on what the specification requires ofthe electro-deposited nickel; i.e. brightness, ductility, thickness,speed of buildup, etc.

It is also well understood in the process of bright nickelelectroplating that in order to obtain pit-free nickel deposits, it isadvantageous to employ agitated, well-filtered solutions. The use of aWetting agent such as sodium lauryl sulfate at concentrations up to 0.25gram per liter also permits the electroplating of pit-free nickeldeposits.

The synthesis of these novel 'brighteners is readily carried out inaccordance With the following procedure:

EXAMPLE I.--ALLYL Z-VINYL PYRIDINIUM BROMIDE CH2=CHCH2Br W 0H=0in NCH=CHz CH2=OH2Cfi2 Br Reagents: Weight (grams) Allyl bromide (1 mol)1260 2-vinyl pyridine (1 mol) 1434 The allyl bromide and vinyl pyridineare mixed with an equal weight of isopropyl alcohol, and the solution isrefluxed for 6-8 hours. Reflux temperature is 78-83 C. The end-point ofthe reaction is determined by titrating for ionic bromide with silvernitrate.

The pyridine compounds areall synthesized in the same fashion. The allylbromide or chloride is reacted with the appropriate pyridine orquinoline in stoichi-ometric proportions and the quaternized compoundrecovered. Thus, allyl bromide is reacted, as in Example I, in a 1:1molar ratio with quinoline, methyl quinoline and vinyl quinolines.

EXAMPLE II To synthesize the N-methallyl 2-vinyl pyridinium bromide, themethallyl bromide is reacted with 2-vinyl pyridi-ne under the conditionsdescribed in Example 1.

EXAMPLE III To make the N-allyl 4-vinyl pyridinium bromide, thephosphate is reacted with the quinoline as in Example I.

EXAMPLE IV Similarly, for making the allyl and methallyl chloridecompounds of 2- and 4-vinyl pyridine, the corresponding allyl andmethallyl chlorides are reacted with the corresponding 2- and '4-vinylpyridines.

The synthesis is the direct stoichiometric reaction carried outcarefully with stoichiometric amounts, so that a good yield is obtained.

Referring to the following tables, in Table I, I have listed thequaternized 2- and 4-vinyl pyridine compounds useful for addition toconventional plating baths as brighteners. I have also indicated thepreferred range of concentration.

In Table II, I have listed a group of preferred sulfur compounds whichare commonly referred to in the trade as primary brighteners. By this ismeant that they are added to the plating bath as brighteners and withthe cyclic nitrogen compounds give a net result which is a substantialimprovement over the effect obtained with either one alone. Thepreferred concentration ranges are also indicated.

Any of the primary brighteners listed in Table II as being typical maybe combined with any of the secondary brighteners of Table I in theconventional acid nickel plating baths. I have tested alarge variety ofcombinations, virtually exhausting the possibilities, and have foundthat, in all cases, an improvement in the brightening effect isobtained. It is also accompanied by an improvement in ductility of thenickel plate. In Table III, I have listed certain of the preferredcombinations, indicating that in any of the conventional Watts typebaths used in the art, or conforming to those indicating herein, thecombination will produce optimum results. Here, it will be noted that insome cases there are two sulfur compounds where the quaternized pyridinecomponents are used. In all cases, the results are characterized by thefact that improvements in brightness, adherence, ductility are obtainedunder ordinary nickel plating conditions.

4 Table II ORGANIC SULFUR ADDITIVES Concentration range,

Compound2 grams/l1 ter Benzene sulfonamide p-Toluenesulfonamide 0.1-2O-benzoylsulfonimide 0.1-1.5 O-carboxybenzenesulfonamide 0.1-2.0 Benzenesulfohydroxamic acid 0.1-2.0 N-benzenesulfonyl iminodiacetic acid0.1-2.0 N-benzenesulfonyl iminodipropionic acid 0.1-2.0 Allyl sulfonicacid 1-10 Vinyl sulfonic acid 1-10 Sodium benzenesulfonate 1-10.0 Sodiummetabenzenedisulfonate l-10.0 1,5 -naphthalene disulfonic acid 1-82,7-naphthalene disulfonic acid 1-8 Naphthalene trisulfonic acid 1-8Table 111 Bath No. Addition Agents Grams] liter N-allyl 2-vinylpyridinium chloride 005 1 o-Benzoyl sulfonamide 1. 0 Paratoluenesnlfonamide 0. 6 N -allyl 4-vinyl pyridinium chloride dibutyl 0092 phosphate.

o-Benzoyl sulfonimide..- 0. N-2 met;hallyl -vinyl py 009 3Benzenesulfonamide. 1. 0 o-Benzoylsulfonimide 1.0 N-allyl2-vinylpyridinium bromide. 0. 01 4 Benzenesulfonamide 1. 0o-Benzoylsulfonimide 1.0 N -ally1 -vinyl pyridinium bron 006 5o-Benzoylsulfonimide 1. 0 Para toluenesulfonamide 0. 6 N-2-1nethallylZ-Vinylpyridininm bromide 0. 01 6 Para toluenesulfonamide 1. 0 o-Benzoylsullonimide. 1. 0 7 N-allyl Z-vinyl pyridinium chloride 0.05 o-Benzoylsulfonimide" 1. 5 8 {N-allyl 4-vinyl pyridinium chloride .009 Allylsulfonic acid... 8.0

What is claimed is: 1. A compound having a formula given by thefollowing:

(IJH=CHQ (I) [ID-011 13112 where R is selected from the group consistingof allyl and methallyl radicals, R is a vinyl group, and X is selectedfrom the group consisting of bromide and chlorine.

. N-Z-methallyl 2-vinyl pyridinium bromide.

. N-allyl 2-vinyl pyridinium bromide.

. N-allyl 4-vinyl pyridinium bromide.

N-2-rnethallyl 4-vinyl pyridinium bromide.

. N-Z-methallyl 2-vinyl pyridinium chloride.

N-allyl 2-vinyl pyridinium chloride.

. N-allyl 4-vinyl pyridinium chloride.

. N-2-Inetha1lyl 4-vinyl pyridinium chloride.

No references cited.

WALTER A. MODANCE, Primary Examiner.

A. L. ROTMAN, Assistant Examiner.

1. A COMPOUND HAVING A FORMULA GIVEN BY HE FOLLOWING :